digestion

• first the food enters the mouth where amylase begins to break down starch
• in the second step, food passes down the oesophagus
• in the third step, food enters the stomach where where protease breaks protein into amino acids.
• the stomach contains hydrochloric acid which helps the enzymes break down the protein
• the churning action of the stomach muscles helps turn food into a fluid, increasing the surface area for enzyme action
• in the third step, the fluid then passes into the small intestine
• also in the third step, the liver produces bile and pancreas releases it (bile helps neutralise the stomach acid)
• also in the third step, the walls of the small intesine release more enzymes to continue the digestion of protein and lipids
• in step four, the small food molecules (glucose, fatty acids, amino acids) are absorbed into the blood either by diffusion or active transport
• in step five, the food is passed into the large intestine and water is absorbed into the bloodstream
• in step six, faeces is passes out of the body through the anus
• the products of the digestive system( fatty acids, amino acids, glucose) are used by the body to build new carbohydrates, lipids and proteins
• some of the glucose produced is used in respiration
• enzymes are a catalyst of digestions
• one enzyme is compatible to one substrate
• the substrate and the enzyme fit together in a lock and key mechanism
• enzymes denature in high temperatures. this denatures the active sight meaning the substrate can no longer fit.
• the optimum temperature for enzyme action is 37